Electrical Conduit Union and Conduit System

ABSTRACT

An electrical conduit piece of the invention has two external threaded regions, one threaded region having a left hand threaded region and one having a right hand threaded region. This conduit piece is particularly well adapted to be used in conventional conduit systems by coupling to conventional conduit pieces through a coupling of the invention having two internal threaded regions, one threaded region having left hand threads and the other threaded region having right hand threads. A groove may be formed in the internal wall of the coupling, e.g., at or near its longitudinal center to provide an open region in which ends of conduit pieces inserted into the coupling can abut. Residing in the grooved region of the coupling is a locking ring which scores the threads of the conduit pieces at 90° preventing any tangential force from outside of the system from unscrewing one of the conduit pieces from the coupling. In a preferred embodiment, the conduit piece is embodied as a curved or elbow conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefits of my;

U.S. patent application 60/169,231 filed Dec. 6, 1999

U.S. patent application 60/169,126 filed Apr. 13, 1999

This application is a continuation of my;

U.S. patent application Ser. No. 10/051,404 filed Jan. 18, 2002, nowabandoned.

REFERENCES CITED

United States Patent Documents

U.S. Pat. No. 4,564,225 Jan. 14, 1986 Taylor 285/333

U.S. Pat. No. 4,091,523 May 30, 1978 Reicke 285/148

U.S. Pat. No. 4,060,264 Nov. 29, 1977 Gajajiva 285/175 X

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to couplings, elbows, nipples andpiping and/or conduit systems and, more particularly, to an electricalconduit system for encasing and protecting flexible wires or cables,such as electrical, optical or communication type cables. An example assuch is defined in National Electrical Code “Rigid Metal Conduit” and“Intermediate Metal Conduit”, Articles No. 344 and No. 342 respectively.The product also is defined in Underwriters Laboratories® Publication #6and #1242, titled respectively, “Rigid Metal Conduit” and “IntermediateMetal Conduit”. In the case of metal conduit, the encasement itself isused as an electrical ground and generally provides redundancy for theseparate internal grounding in the event that one of the internalcharged wires contacts the internal system.

Description of the Currently Available Technology

In construction and architectural applications, electrical conduitsystems are used to encase and protect flexible lines or cables, such aselectrical power lines, telephone lines, fiber optic cables, computernetwork cables, etc., to prevent damage to these lines. Such electricalconduit systems are used within buildings, e.g., within the walls ofbuildings, underground, and for exposed above-ground outdoorapplications. Conventional electrical conduit systems consist ofindividual conduit sections or pieces usually made of rigid material,such as galvanized or stainless steel, PVC, or aluminum, coupledtogether to form the conduit system, generally referred to as a “conduitrun”.

Examples of standard electrical conduit pieces include straight conduitsections, for example ten foot sections of conduit of various diameterswith exterior or male threads on each end; so-called “nipples”, i.e.,shorter straight conduit sections of various diameters with exterior ormale threads on each end; and elbows, i.e., bent or curved conduitsections also with exterior or male threads on each end. By standardconvention, the threads on the ends of the conventional conduit piecesare all right hand threads. Adjacent conduit pieces are connectedtogether by a female coupling having continuous, internal right handthreads.

To construct a conventional electrical conduit system, a first conduitpiece, e.g., a nipple, is secured at one end of the conduit run, usuallyat the feed end. A female coupling is screwed onto the outer end of thefirst conduit piece until seated. Then, a second conduit piece, forexample a straight ten-foot section or an elbow, is inserted into theother end of the female coupling and turned to thread it into the femalecoupling to connect the second conduit piece to the first conduit piece.Additional conduit pieces, connected by additional female couplings, aresuccessively added to form the electrical conduit system. The sectionsor pieces may be attached to walls or suspended from a ceiling byvarious known methods. Typically, offsets (or elbows) are required inthe “run” that cannot be rotated about the longitudinal axis.

While generally acceptable for protecting cables, there are limitationsassociated with conventional electrical conduit pieces and electricalconduit systems. For example, in conventional systems each conduit piecemust be successively coupled to the previous conduit piece. Once theconduit system is formed, it is difficult to reenter or access anintermediate section of the conduit system. Such reentry typicallyentails complete disassembly of the conduit system from one end to thepoint of desired access. This disassembly can be costly and laborintensive.

Alternatively, for complex conduit runs, access is sometimes gained tointermediate sections by destructive means, generally involving pipecutting and wire pulling or cutting. However, this creates a problem,particularly in confined areas such as the interior of walls, in thatthe destroyed section of conduit cannot generally be replaced with thesame type of conduit pieces since there is not sufficient room to threadthe conduit pieces together, i.e., there is insufficient room to rotatethe new conduit pieces, particularly curved conduit pieces, into thecoupling.

Additionally, to connect conventional conduit pieces together theconduit pieces must be rotated or turned to thread the end of oneconduit piece into the adjacent female coupling. Since conventionalconduit pieces can weigh on the order of several hundred pounds, severalworkers may be required to align and rotate larger conduit pieces. Thisrotation is particularly difficult with large elbow pieces which, inaddition to the problem of their weight, also require enough clearanceroom, especially from wall installations, for the curved outer sectionof the elbow to rotate while threading an end of the elbow into aconventional female coupling. The turning of such large conduit piecesincreases the manpower requirement to form a conventional electricalconduit system and, hence, increases the cost of construction.

Further, since the conventional conduit pieces must be rotated duringconstruction of the electrical conduit system, the cable or cables to beprotected cannot be pre-positioned inside the disassembled conduitpieces. Rather, after the entire conduit system has been constructed,the cable is typically pulled through the entire conduit system from oneend to the other. This pulling may damage the cable and is particularlydisadvantageous for fiber optical cables. For example, many conventionalfiber optic cable systems have four or more spaced fiber optic cablespassing through the conduit system. These fiber optic cables are held inplace by spacers in the conduit pieces. Because the conventional conduitpieces must be rotated to form the conduit system, the fiber opticcables cannot be inserted into the conduit pieces until the entireconduit system has been constructed to prevent twisting or damage to thecables. However, pulling the fiber optic cables through the entiresystem presents an opportunity for the fiber optic cables to be broken,damaged or misaligned.

Therefore, several complex clamping devices are commonly employed. Onesuch device comprises of a split sleeve with an internal threaded regionon both sections. The device is bolted over the external threaded regionof two components thereby connecting them. Another device, referred toas an “Erickson” coupling, is comprised of a first sleeve with ainternal threaded portion and an internal flange. The first sleeve isslipped over the end of one of the conduit sections and second sleeve isthreaded onto the end of the same conduit. The third sleeve is comprisedof an interior threaded portion and an exterior flange and threadedsurface. The interior threaded portion of the third sleeve is threadedonto a second conduit piece. The first sleeve slipped back along thefirst conduit, fitted over the second sleeve and subsequently rotated orthreaded onto the third sleeve. A secure joint is completed as thesecond sleeve abuts the interior flange of the first sleeve, the firstsleeve being threaded against the exterior flange of the third sleeve. Athird method is also employed using the device described in U.S. Pat.No. 4,091,523, (Reicke, 29/525.11). The description of the device fromthe abstract cites: A sleeve having first and second interior surfaceportions. The first surface portion is threaded and communicates withone open end of the sleeve., the second surface portion is smooth andcommunicates with the opposite open end of the sleeve. A bore is formedthrough the sleeve and the second surface portion thereof, and a setscrew is threaded into the bore. The sleeve is first slipped, and thenthreaded, onto a first conduit, the conduit being first received by thesmooth interior surface and then by the threaded interior surface. Theend of the second conduit is the disposed adjacent the sleeve, and thesleeve is screwed back off the first conduit onto the second conduituntil the first conduit is received by the smooth interior surface andthe second conduit by the threaded interior surface. The set screw isthreaded against the first conduit.

However, these known clamping devices are generally expensive topurchase and install. They posses the additional disadvantage of beingmore bulky than the original conduit run, thereby requiring a largerfree space between parallel or adjacent conduit runs, or a larger freespace within confined areas such as within walls, than wouldconventional conduit pieces. Further, the aforementioned devices consistof numerous parts which may become misplaced or lost. Additionally,several of the devices may not be used in certain types ofinstallations, such as explosion proof installations as defined by thevarious electrical codes, which require sufficient thread engagement tocool flame under pressure. In addition, the conduit sections must abutone another to prevent the current from an electrical short from arcingacross the conduit section to the coupling and arcing back across thecoupling to the conduit section.

Another device, Gajajiva, U.S. Pat. No. 4,060,264, provides a swivelcoupling with a resilient seal and non-centered recess which forces anon-arcing ground and provides insufficient thread engagement forstricter code installations.

Therefore, it would be advantageous to provide an electrical conduitpiece and/or conduit system which reduces or eliminates the limitationsassociated with conventional electrical conduit systems, beingacceptable for the strictest levels of the electrical code and fittingwithin the same minimal dimensional areas as the basic conduit run.

Also, Underwriters Laboratories® has investigated the elbow and nippleembodiments of the invention for rigid galvanized and aluminum conduitunder UL-6 and accepted the design as conforming with the standard.

SUMMARY OF THE INVENTION

A conduit system of the invention comprises a plurality of conduitpieces, at least one of the conduit pieces comprising a first conduitpiece having a first end with a first threaded region and a second endwith a second threaded region. A coupling of the invention is configuredto engage at least one end of the first conduit piece and one end of anadjacent conduit piece. The coupling comprises a first threaded portionand a second threaded portion, with a groove region located therebetweenand with the first threaded portion of the coupling being of differentthread direction than the second threaded portion, the recess beingnecessary for the pieces to abut while maintaining sufficient threadengagement for conduit fittings. The locking ring of the inventioncomprises an open ended ring with spring like characteristics and coarseinternal threads, which, when seated in the internal grooved section ofthe coupling lie perpendicular to the threaded portion of the couplingand conduit piece. The locking ring is unattached to the coupling andremains in place by spring tension.

Another conduit system of the invention comprises a plurality of firstconduit pieces, each having a first end with a first threaded region anda second end with a second threaded region. The first and secondthreaded regions have substantially the same first thread direction. Atleast one second conduit piece is provided having a first end with afirst threaded region and a second end with a second threaded region,with the first and second threaded regions of the second conduit pieceeach having substantially the same second thread direction and with thesecond thread direction being different than the first thread direction.At least one coupling is provided and comprises a first threaded portionand a second threaded portion, with the first threaded portion having adifferent thread direction than the second threaded portion, with thefirst threaded portion of the coupling configured to reversibly engagethe first threaded region on the first conduit piece, and with thesecond threaded portion of the coupling configured to reversibly engagethe second threaded region on the second conduit piece to reversiblycouple the first conduit piece with the second conduit piece. As thefirst threads of the two conduit pieces enter the internal grooved area,the coarse threads of the locking ring score the threads of the twoconduit pieces at 90° until the rotation of the coupling part forces theends of the two conduit pieces to abut.

A further conduit system is provided comprising a plurality of firstconduit pieces having a first end and a second end, with firstexternally threaded regions located at each end, and with each firstthreaded region comprising right hand threads. A plurality of secondconduit pieces is provided, each having a first end and a second end,with second, externally threaded regions located at each end, eachsecond threaded region comprising left hand threads. A coupling islocated between adjacent first and second conduit pieces and isconfigured to reversibly engage one end of the first conduit piece withone end of the adjacent second conduit piece, the coupling comprising afirst, internally threaded, right hand thread portion configured toengage an end of a first conduit piece and a second, internallythreaded, left hand thread portion configured to engage an end of asecond conduit piece. The coupling has an internal groove regionpositioned such that when the coupled ends of the first and secondconduit piece are inserted into the coupling, the inserted ends of theconduit pieces abut in the internal groove region. As the first threadsof the two conduit pieces enter the internal grooved area, the coarsethreads of the locking ring score the threads of the two conduit piecesat 90° until the rotation of the coupling part forces the ends of thetwo conduit pieces to abut.

An additional conduit system is provided

A method of forming a conduit system of the invention comprises thesteps of providing a plurality of first conduit pieces, each firstconduit piece having a first end with a first threaded region and asecond end with a second threaded region, with the first and secondthreaded regions having the same first thread direction; providing atleast one second conduit piece having a first end with a first threadedregion and a second end with a second threaded region, with the firstand second threaded regions of the second conduit piece being of thesame second thread direction, and with the second thread direction beingdifferent from the first thread direction; providing a coupling having afirst threaded portion and a second threaded portion, with the threaddirection of the first and second threaded portions being different fromeach other; engaging the first threaded portion of the coupling with afirst threaded region on a first end of a first coupling piece; engagingthe second threaded portion of the coupling with a second threadedregion on a second end of the second coupling piece; and rotating thecoupling in a first direction to thread the first end of the firstcoupling piece and second end of the second coupling piece into thecoupling until the coupled ends of the conduit pieces abut. As the firstthreads of the two conduit pieces enter the internal grooved area, thecoarse threads of the locking ring score the threads of the two conduitpieces at 90° until the rotation of the coupling part forces the ends ofthe two conduit pieces to abut.

A method of retrofitting a conduit system having a plurality of firstconduit pieces with opposed ends and threaded regions of the same threaddirection located on each end is provided. The first conduit pieces arecoupled by first couplings having opposed ends with threaded portions ofthe same thread direction as the threaded regions of the first conduitpieces. The method comprises the steps of removing at least one firstconduit piece and at least one of the first couplings; replacing theremoved first conduit piece with a second conduit piece having a firstend and a second end, the first end having a first threaded region ofthe same direction as the first conduit piece and the second end havinga second threaded region of different thread direction than the firstthreaded region; replacing the removed first coupling with a secondcoupling, the second coupling comprising a first threaded portion havingthe same thread direction as the first threaded region of the secondconduit piece and a second threaded portion of the same thread directionas the second threaded region of the second conduit piece; engaging thesecond threaded portion of the coupling with the second end of thesecond conduit piece; engaging the first threaded portion with an end ofan adjacent first conduit piece; and rotating the second coupling toengage the second end of the second conduit piece with the adjacent endof a first conduit piece until the coupled ends of the first and secondconduit pieces substantially abut. As the first threads of the twoconduit pieces enter the internal grooved area, the coarse threads ofthe locking ring score the threads of the two conduit pieces at 90°until the rotation of the coupling part forces the ends of the twoconduit pieces to abut.

An electrical conduit piece of the invention has threaded regions,particularly external, left hand, tapered or straight threaded regionsat each end. This conduit piece is particularly well adapted to be usedin conventional conduit systems by coupling to conventional conduitpieces through a coupling of the invention having two internal threadedregions, one threaded region having left hand threads and the otherthreaded region having right hand threads. A groove may be formed in theinternal wall of the coupling, e.g., at or near its longitudinal centerto provide an open groove region in which ends of conduit piecesinserted into the coupling can abut. A locking ring is provided in theinvention to prevent either one of the conduit ends from becomingunthreaded should tangential force be applied to rotate one of theconduit pieces at some point outside the system through improperinstallation. In a preferred embodiment, the conduit piece is embodiedas a curved or elbow conduit and would not need the locking ring.

A further embodiment of the invention comprises a conduit piece havingexternal, right hand threads at one end and external, left hand threadsat the other end. The conduit pieces and coupling of the invention canbe used in constructing new electrical conduit systems or inretrofitting existing conduit systems.

A complete understanding of the invention will be obtained from thefollowing description when taken in connection with the accompanyingdrawing figures wherein like reference characters identify like partsthroughout.

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a plan view of a conduit piece (not to scale) of theinvention;

(2) FIG. 2 is a longitudinal, sectional view (not to scale) of acoupling of the invention;

(3) FIG. 3 is a plan view of the conduit piece (not to scale) of FIG. 1connected by the coupling of FIG. 2 to a conventional conduit section;

(4) FIG. 4 is a schematic view of an electrical conduit system (not toscale) utilizing a conduit piece and couplings of the invention;

(5) FIG. 5 is a plan view of an alternative conduit piece (not to scale)of the invention; and

(6) FIG. 6 is a side, sectional view of the upper part of a coupling ofthe invention (not to scale) showing an exemplary thread profile.

(7) FIG. 7 is a plan view of the locking ring (not to scale) prior tobeing formed.

(8) FIG. 8 is plan view of the locking ring (not to scale) after beingformed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, and similar spacial terms shall relate to the inventionas it is oriented in the drawing figures. However, it is to beunderstood that the invention may assume various alternativeorientations and step sequences, unless expressly stated to thecontrary. It is also to be understood that the specific dimensionsillustrated in the attached drawings and described in the followingspecification are simply exemplary embodiments of the invention and arenot to be considered as limiting.

A conduit piece of the invention is generally designated 10 in FIGS. 1,3 and 4. As shown in FIG. 1, the conduit piece 10 is formed of a hollow,substantially cylindrical body 12 made of rigid material, such as PVC ormetals such as stainless steel, galvanized carbon steel or aluminum, orsimilar materials. The conduit piece 10 has a first end 14 and a secondend 16. A first threaded region 18 is formed on the outer surface of theconduit piece 10 at or near the first end 14 and a second externallythreaded region 20 is formed at or near the second end 16 of the conduitpiece 10. In the preferred embodiment of the invention, the threadedregions 18 and 20 are both comprised of threads having the same threaddirection, e.g., left hand, tapered or straight threads. While theconduit piece 10 in FIG. 1 is shown as a curved or elbow conduit, it isto be understood that the conduit piece 10 is not limited to elbowconduits but may be of any conventional electrical conduitconfiguration, e.g., a straight conduit section. The conduit piece 10 ispreferably of substantially the same dimensions as standard conventionalconduit pieces known in the art.

A hollow coupling of the invention is generally designated 24 in FIGS.2-4. The coupling 24 is preferably substantially cylindrical and may bemade from the same materials as the conduit piece 10. The coupling 24has a first end 26 and a second end 28. An internal recess 30, i.e., aregion of larger internal diameter than the central region of thecoupling 24, is formed at or near each end 26 and 28 of the coupling 24.The coupling 24 further includes a first internally threaded portion orregion 32 and a second internally threaded portion or region 34. Asshown in FIG. 2, a first tapered region 36 is located between the leftrecess 30 and the first threaded region 32 and a second tapered region38 is located between the right recess 30 and the second threaded region34. The threaded regions 32 and 34 are preferably comprised of taperedor straight threads of opposed thread directions, e.g., the firstthreaded region 32 may be comprised of right hand threads and the secondthreaded region 34 may be comprised of left hand threads. The threadedregions 32 and 34 are preferably of substantially the same length, whichthread length preferably substantially corresponds to the length of thethreaded regions 18 and 20 on the conduit piece 10. Preferably eachthreaded region 32 and 34 is configured to provide nine full engagementthreads so that the system of the invention meets the requirements ofUL®-6 and qualifies as a class one conduit installation.

An internal circumferential groove 40 is formed in the internal wall ofthe coupling 24 and is preferably located approximately at or near thelongitudinal center of the coupling 24. The groove 40 provides an opengroove region in which the ends of conduit pieces inserted into thecoupling 24 can abut. For example, FIG. 2 shows two conduit pieces A andB (in phantom) engaged with the coupling 24. The inner end C of conduitpiece A abuts the inner end D of conduit piece B in the open areacreated by the groove 40. This is required for a good ground for thesystem.

A locking ring of the invention is generally designated 76 in FIGS. 7and 8. The locking ring resides in the internal grooved section 40, FIG.2, and is held in place by spring tension. The locking ring has coarseinternal threads 77,which score the threads at 90° of any conduit pieceupon its reaching section 40 while still allowing the two conduit endsto abut. This, coupled with the friction created by the abutment of theconduit pieces, prevents any tangential force exerted upon either one orthe other conduit pieces from outside of the system from causing thatparticular conduit piece to become unscrewed. Such an event could becaused by improper installation of straight pieces to one of theembodiments of the invention.

Use of the conduit piece 10 and coupling 24 of the invention will now bedescribed. FIG. 3 shows how the conduit piece 10 may be coupled bycouplings 24 to conventional conduit pieces or sections 42, e.g.,straight conduit sections having opposed ends with threaded regions ateach end each threaded region being of the same thread direction, e.g.,conventional right hand threads. Looking at the lower coupling 24 inFIG. 3, for example, the first end 26 of the coupling 24 is slipped ontothe outer end (first end) of the lower conduit section 42 until theright hand threads on the conduit section 42 contact, abut or initiallyengage the right hand threads on the first threaded region 32 of thecoupling 24. One end, for example the second end 16, of the conduitpiece 10 is then inserted into the second end 28 of the coupling 24until the left hand threads on the second end 16 of the conduit piece 10contact, abut or initially engage the left hand threads on the secondthreaded region 34 of the coupling 24. Next, the coupling 24 is rotatedor turned to simultaneously thread the second end of the conduit piece10 and first end of the conduit section 42 into the coupling 24 untilthe inserted ends of the conduit piece 10 and conduit section 42 abut insimilar manner as the conduit pieces A and B in FIG. 2. During thisprocedure, only the coupling 24, not the conduit piece 10 or conduitsection 42, rotates to reversibly couple the conduit piece 10 andconduit section 42. As used herein, the terms “reversibly couple” or“reversibly engage” mean that the coupled conduit pieces can beuncoupled by rotating the coupling 24 in an opposite direction to thatused to couple the pieces together.

The recesses 30 permit a small amount of float or play in case therespective ends of the conduit piece 10 and conduit section 42 beingcoupled are not started at exactly the same thread position in theopposed ends 26 and 28 of the coupling 24. The first end 14 of theconduit piece 10 can be similarly connected to the outer end of theupper conventional conduit section 42 by another coupling 24 of theinvention, with the second coupling region 34 {left hand threads) of theupper coupling 24 engaging the left hand threads on the first end 14 ofthe conduit piece 10 and the first coupling region 32 (right handthreads) of the upper coupling 24 engaging the right hand threads on theouter (first or second) end of the upper conventional conduit section42. Thus, the elbow-shaped piece 10 does not itself have to be rotatedto be connected into an electrical conduit system utilizing standardright hand threaded straight conduit sections 42. This is particularlyadvantageous with larger elbow-shaped conduit pieces 10, which, inpreviously known systems, would have to be physically rotated andsupported, usually by a crew of workers. Additionally, previously knownelbow sections could only be placed in areas with sufficient clearanceto allow the elbow to be rotated. In the present invention, only thecoupling needs to be rotated, not the elbow itself. This greatly reducesthe manpower required for coupling large, particularly elbow-shaped,conduit pieces or sections which, in turn, lowers the cost ofconstructing a conduit system.

An electrical conduit system utilizing conduit pieces 10 and couplings24 of the invention is designated 50 in FIG. 4. The conduit system 50extends from a junction box or breaker box 52 to an outlet or breaker54. In the conduit system 50 shown in FIG. 4, conventional conduitsections 42 having right hand external threaded regions may be used in5he construction of the conduit system 50. For example, the conduitsystem 50 may be initially constructed as follows. A conventional nipple56 can be connected to the breaker box 52. A first conduit piece 10 a ofthe invention is then connected to the nipple 56 by a first coupling 24in similar manner as described above. A second conventional conduitsection 42 b is then connected to the first conduit piece 10 a by asecond coupling 24 and so on until the electrical conduit system 50 hasbeen constructed. By alternating coupling conduit pieces 10 of theinvention and conventional conduit sections 42 by coupling pieces 24 ofthe invention, the entire conduit system 50 may be constructed withoutthe need to rotate the conduit pieces 10 or conduit sections 42themselves. This greatly reduces the manpower required for constructionof the conduit system 50. Further, since none of the conduit pieces 10or sections 42 needs to be rotated, the flexible member, e.g., wire orcable being encased, can be pre-staged or threaded through therespective disassembled conduit pieces 10 or sections 42 beforeassembly. This means that the cable does not have to be pulled throughthe finally constructed system and thus reduces the chances of damagingthe cable. This is particularly useful with respect to fiber opticcables.

Another advantage of the conduit system 50 over known systems is thatthe intermediate portion of the conduit system 50 can be easily accessedto examine or repair specific parts of the cable or to add additionalconduit runs or branches without having to disassemble the entireconduit system 50 from one end. For example, a coupling 24 can berotated to disassemble the end of one of the conduit pieces 10 from theassociated end of an adjacent conduit section 42. All that is requiredis sufficient clearance of about a thread length, i.e., the length of athreaded region 18 or 20, to allow the end of the selected conduit piece10 to be withdrawn from the coupling 24. The other end of the conduitpiece 10 could then also be disassembled in a similar manner by simplyrotating the coupling 24 on the other end of the coupling piece 10.

Alternatively, the conduit piece 10 and couplings 24 of the inventioncan be retrofitted into an existing electrical conduit system. Forexample, the cable of the system can be pulled back from one end throughthe region to be accessed. An existing conduit section having right handthreaded ends can then be removed, such as by cutting, and replaced witha conduit piece 10 and couplings 24 of the invention. This would beparticularly useful in retrofitting electrical conduit systems havingelbow-shaped pieces located in confined areas, such as within buildingsor within the walls of buildings, where portions of the building wouldnormally have to be destroyed to allow sufficient clearance to add orreplace an elbow section. This reduces the cost of replacing orretrofitting existing conduit systems. Further, the present invention isalso well adapted for use in upgrading or reworking existing electricalconduit systems, such as by adding branch lines. For example, to-add abranch line to the conduit system 50 of FIG. 4, one or more of theconduit pieces 10 can be removed as described above and replaced with aconventional junction or branch line. Additionally, since the conduitpiece 10 and coupling 24 of the invention can be used with existingconventional right hand threaded conduit sections, the existinginventory of conventional conduit sections can still be used.

An alternative embodiment of a coupling piece of the invention isdesignated 60 in FIG. 5. The coupling piece 60 is configured as astraight conduit piece having a first end 62 with an external, firstthreaded region 64 and a second end 66 with an external, second threadedregion 68. However, in this embodiment, the first threaded region 64 iscomprised of left hand threads and the second region 68 is comprised ofright hand threads. The coupling piece 60 is particularly well adaptedto be placed in the straight section of a conduit run at a position thebuilder may later wish to access, for example to place a junction box orbranch line. The second end 66 of the conduit piece 60 with right handthreads may be conventionally connected to a conventional conduitsection with a conventional coupling. However, the first end 62 of theconduit piece 60 can be attached by a coupling 24 of the invention withan adjacent conventional conduit section. This section of the conduitrun can be later accessed simply by uncoupling the coupling 24, i.e.,rotating the coupling to disengage the first end 62 from the adjacentconduit section and then removing the conduit piece 60 from theconventional coupling by rotating the conduit piece 60.

Another particularly well-adapted use of the coupling piece 10 andcouplings 24 of the invention is in electrical conduit systems forbridge decks encasing fiber optic cables. Presently, the bridge deckconduit sections for fiber optic cables are connected by a complex,right hand threaded coupling. However, these conventional bridge deckcouplings can typically be removed by hand or with nothing more than ascrewdriver, allowing unauthorized access to the fiber optic orcommunication cables running through the bridge deck electrical conduitsystem. This provides little or no protection against vandalism of thecables. However, the present invention can improve this protection. Byconstructing a bridge deck electrical conduit system utilizing theconduit piece 10 and couplings 24 of the invention but which does notallow sufficient Clearance to uncouple the end of a conduit piece 10from an adjacent coupling 24, the bridge deck conduit system cannot beaccessed.

It will be readily appreciated by those skilled in the art thatmodifications may be made to the invention without departing from theconcepts disclosed in the foregoing description. Such modifications areto be considered as included within the scope of the invention.Accordingly, the particular embodiments described in detail herein areillustrative only and are not limiting to the scope of the invention,which is to be given the full breadth of the appended claims and any andall equivalents thereof.

1. A conduit system, comprising of a plurality of first conduit pieces,each first conduit piece having a first end with a first threaded regionand a second end with a second threaded region, with the first andsecond threaded regions having substantially the same first threaddirection; at least one second conduit piece having a first end with afirst threaded region and a second end with a second threaded region,with the second thread direction being different than the first threaddirection; and at least one coupling, the coupling comprising a firstthreaded portion and a second threaded portion containing a specificallysized recess therebetween, with the first threaded portion having adifferent thread direction than the second threaded portion, with thefirst threaded portion of the coupling configured to reversibly engagethe first threaded region on the first conduit piece and with the secondthreaded portion of the coupling configured to reversibly engage thesecond threaded region on the second conduit piece to reversibly couplethe first conduit piece with the second conduit piece; and insureabutment of the ends of the two conduit pieces within the specificallysized recess, providing an electrical ground which does not pass throughthe coupling and, at least one locking ring comprising a coarse threadedportion, the threaded portion being oriented to the inside of the ringand the threads of said ring being aligned nearly perpendicular to thethreads of the first and second conduit piece, with the ring beingformed to less than 360° and formed from a material having spring likecharacteristics. The system further provides the specified amount ofthread engagement to meet the various sealing and cooling capabilitiesrequired the various electrical codes in their stricter requirements.The system further provides a conduit installation that is not largerthan any part of a normal installation and allows the closest parallelconduit runs allowed within the size of conduit run.
 2. A conduitsystem, comprising of a plurality of first conduit pieces having a firstend and a second end, with first externally threaded regions located ateach end, each first threaded region comprising right hand threads; aplurality of second conduit pieces having a first end and a second end,with the second externally threaded regions located at each end, eachsecond threaded region comprising left hand threads; and a couplinglocated between adjacent first and second conduit pieces and configuredto reversibly engage one end of a first conduit piece with one end of anadjacent second conduit piece, the coupling comprising a first,internally threaded, right hand thread portion configured to engage anend of a first conduit piece and a second, internally threaded, lefthand thread portion configured to engage an end of a second conduitpiece, the coupling having a specifically sized internal groove regionpositioned such that when the coupled ends of the first and secondconduit piece are threaded into the coupling, the inserted ends abut inthe internal groove region providing an electrical ground which does notpass through the coupling and a locking ring abiding in the internalgrooved region of the coupling and as the inserted ends of the conduitpieces enter the grooved region, they are scored at nearly 90° by thecoarse threads of the locking ring. The system further provides thespecified amount of thread engagement to meet the various sealing andcooling capabilities required the various electrical codes in theirstricter requirements. The system further provides a conduitinstallation that is not larger than any part of a normal installationand allows the closest parallel conduit runs allowed within the size ofconduit run.
 3. A method of forming a conduit system, comprising thesteps of: providing a plurality of first conduit pieces, each firstconduit piece having a first end with a first threaded region and asecond end with a second threaded region, with the first and secondthreaded regions having the same first thread direction; providing atleast one second conduit piece having a first end with a first threadedregion and a second end with a second threaded region, with the secondthread direction being different from the first thread direction;providing a coupling having a first threaded portion and a secondthreaded portion, with the thread direction of the first and secondthreaded portions being different from each other and having an internalgrooved region between and the first and second threaded portions;engaging the first threaded portion of the coupling with a firstthreaded region on a first end of a first coupling piece; engaging thesecond threaded portion of the coupling with a second threaded region ona second end of the second coupling piece; and rotating the Coupling ina first direction to thread the first end of the first coupling pieceand second end of the second coupling piece into the coupling until thethreads are scored by the locking ring and the ends abut. The systemfurther provides the specified amount of thread engagement to meet thevarious sealing and cooling capabilities required the various electricalcodes in their stricter requirements. The system further provides aconduit installation that is not larger than any part of a normalinstallation and allows the closest parallel conduit runs allowed withinthe size of conduit run.
 4. The method of claim 3, wherein the couplinghas an internal groove region and the method comprises rotating thecoupling such that the ends of the first and second conduit pieces arescored by the locking ring and abut in the groove region.
 5. The methodof claim 3, including rotating the coupling in a second direction todisengage the first conduit piece from the second conduit piece.
 6. Themethod of claim 3, including inserting a flexible member through thefirst and second conduit pieces and the coupling before coupling theconduit pieces together.
 7. A method of retrofitting a conduit systemhaving a plurality of first conduit pieces with opposed ends andthreaded regions of the same thread direction located on each end, thefirst conduit pieces being coupled by first couplings having opposedends with threaded portions of the same thread direction as the threadedregions of the first conduit pieces, the method comprising the steps of:removing at least one first conduit piece and at least one of the firstcouplings; replacing the removed first conduit piece with a secondconduit piece having a first end and a second end, the first end havinga first threaded region of the same direction as the first conduit pieceand the second end having a second threaded region of different threaddirection than the first threaded region; replacing the removed firstcoupling with a second coupling, the second coupling comprising a firstthreaded region having the same direction as the first threaded regionof the second conduit piece and a second threaded portion of the samethread direction as the second threaded region of the second conduitpiece; engaging the second threaded portion of the coupling with thesecond end of the second conduit piece; engaging the first threadedportion with an end of an adjacent first conduit piece; and rotating thesecond coupling to engage the second end of the second conduit piecewith the adjacent end of a first conduit piece until the coupled ends ofthe first and second conduit pieces are scored at nearly 90° by thelocking ring.
 8. The method of claim 7, wherein the second couplingcomprises a groove region wherein resides a locking ring and the coupledends of the conduit pieces abut in the groove region.